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Pliosaurs
The Pliosaur is a type of large carnivorous marine reptile belonging to the plesiosaur family. They were truly enormous creatures of the deep that fed on fish and smaller sea dinosaurs or marine reptiles, such as elasmosaurs and ichthyosaurs. Unfortunately for researchers, the only part of any particular pliosaur that remains in fossilization is the skull. Fortunately, though, the scientists are able to use the skull of the creature as a guide to help determine how the pliosaur looked. Scientists have been able to build models and have come up with their best assumptions as to how the pliosaurs actually looked. There are mainly two varieties of pliosaur, the Liopleurodon and the Kronosaurus. The different varieties of pliosaur have the same basic physical appearance. They are all very large, have a short neck, large head, and four large fins. The main difference is in the length of their body and the proportionality of the animal's head to its body. For the Kronosaurus, there are two physiological possibilities. For the Liopleurodon, there is one. The Liopleurodon is the larger of the two and is somewhat less common than the Kronosaurus. There are also several other varieties of pliosaur. There are also other varieties of pliosaur, including the Rhomaleosaurus, Macroplata, the Simolestes, Thalassiodracon, and the Svalbard Pliosaur. Assumed Physiology Because only the skulls of these massive creatures were able to remain intact in fossilization, the exact physiology of the pliosaur is not known. Using the skulls to determine the animal's appearance, scientists have come up with an assumed physiology for the pliosaurs. There are about seven different types of pliosaur, all having a different physical appearance. Kronosaurus When the Kronosaurus' skull's were first discovered, scientists believed that the skulls were a little less than one quarter of the creature's entire body. This leads them to the conclusion that the monsterous animal's whole body reached a total length of an impressive 12-14 meters (40-46 ft.). After much more research, more recent studies of pliosaurs suggest that Kronosaurus' head was only one third of its entire body length, significantly decreasing its size. With this research, scientists now believe that the Kronosaurus' total body length was around 8 meters (26 ft.), making it six meters (20 ft.) shorter. Despite this, Kronosaurus is still enormous compared to most. Liopleurodon The whole body length of the Liopleurodon is around 11 meters (38 ft.) long. Unlike the Kronosaurus, the Liopleurodon's head was one fifth of its entire body length. Four strong paddle-like limbs suggest that Liopleurodon was a powerful swimmer. Its four-flipper mode of propulsion is characteristic of all plesiosaurs. A study involving a swimming robot has demonstrated that although this form of propulsion is not especially efficient, it provides very good acceleration - a desirable trait in an ambush predator. Studies of the skull have shown that it could probably scan the water with its nostrils to ascertain the source of certain smells. Macroplata The Macroplata was a pliosaur that thrived during the early Jurassic Period. It was a smaller pliosaur, only reaching about 4.5 meters (15 ft.) in total body length. Like all other pliosaurs, Macroplata lived on a diet of fish and smaller plesiosaurs. Macroplata had large shoulder bones, indicating a powerful forward stroke for fast swimming and easy acceleration. Unlike other pliosaurs, Macroplata had a relatively long neck. Their neck was twice the length of the skull, much longer in contrast to later pliosaurs. Rhomaleosaurus Rhomaleosaurus was a somewhat larger variety of pliosaur that thrived during the early Jurassic Period. It was about 7 meters (20 ft.) long in total body length. Like all pliosaurs, it was a carnivorous marine reptile. But unlike the others, Rhomaelosaurus was able to pick up scents when submerged by forcing water to its sensory organs through passages in its skull. This very useful adaptation enabled it to hunt its prey in a similar manner as some modern shark species. This made Rhomaleosaurus a very efficient hunter, and better off than other plesiosaurs of its time. Thalassiodracon Thalassiodracon was a very small variety of pliosaur that only reached 1.5 to 2 meters (5-6.5 ft.). The Thalassiodracon lived during the late Triassic Period to the early Jurassic Period. The skull of the Thalassiodracon was only one tenth the size of its total body length, where most pliosaurs had proportionally larger skulls. Being smaller than the other varieties of pliosaur, it was not able to have the same diet. Instead of feeding on other plesiosaurs and ichthyosaurs, Thalassiodracon's diet consisted mostly of small fish and other under-sea creatures. Simolestes The Simolestes were a genus of pliosaurs that consisted of three distinct species of pliosaur that lived in the seas that covered modern day Europe during the middle to late Jurassic Period. Although the three Simolestes' sizes vary slightly, they are all large pliosaurs. Like most pliosaurs, they were carnivorous marine reptiles that had a short neck, four large flippers made for accelleration, and a large head with sharp teeth for grabbing its prey, which consisted of fish and smaller pleisiosaurs. Svalbard Pliosaur In February of 2008, the University of Oslo announced the discovery of the largest dinosaur-era marine reptile ever found. This creature was the Svalbard Pliosaur. Its total body length was about 15 meters (50 ft.) long. The Svalbard Pliosaur was the largest pliosaur ever found. Like all pliosaurs, it was a carnivorous marine reptile that probably fed on fish and other plesiosaurs. This massive creature was anatomically the same most pliosaurs. It mostly resembles the Kronosaurus, but it was much larger. The image to the right is an example of its size, compared to the Kronosaurus. Category:Marine reptiles